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![Kirill A. Shutemov](/assets/img/avatar_default.png)
Events should be removed after rmdir of cgroup directory, but before destroying subsystem state objects. Let's take reference to cgroup directory dentry to do that. Signed-off-by: Kirill A. Shutemov <kirill@shutemov.name> Acked-by: KAMEZAWA Hiroyuki <kamezawa.hioryu@jp.fujitsu.com> Cc: Paul Menage <menage@google.com> Acked-by: Li Zefan <lizf@cn.fujitsu.com> Cc: Balbir Singh <balbir@linux.vnet.ibm.com> Cc: Pavel Emelyanov <xemul@openvz.org> Cc: Dan Malek <dan@embeddedalley.com> Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
630 lines
18 KiB
C
630 lines
18 KiB
C
#ifndef _LINUX_CGROUP_H
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#define _LINUX_CGROUP_H
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/*
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* cgroup interface
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*
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* Copyright (C) 2003 BULL SA
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* Copyright (C) 2004-2006 Silicon Graphics, Inc.
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*
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*/
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#include <linux/sched.h>
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#include <linux/cpumask.h>
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#include <linux/nodemask.h>
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#include <linux/rcupdate.h>
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#include <linux/cgroupstats.h>
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#include <linux/prio_heap.h>
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#include <linux/rwsem.h>
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#include <linux/idr.h>
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#ifdef CONFIG_CGROUPS
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struct cgroupfs_root;
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struct cgroup_subsys;
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struct inode;
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struct cgroup;
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struct css_id;
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extern int cgroup_init_early(void);
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extern int cgroup_init(void);
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extern void cgroup_lock(void);
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extern int cgroup_lock_is_held(void);
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extern bool cgroup_lock_live_group(struct cgroup *cgrp);
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extern void cgroup_unlock(void);
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extern void cgroup_fork(struct task_struct *p);
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extern void cgroup_fork_callbacks(struct task_struct *p);
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extern void cgroup_post_fork(struct task_struct *p);
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extern void cgroup_exit(struct task_struct *p, int run_callbacks);
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extern int cgroupstats_build(struct cgroupstats *stats,
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struct dentry *dentry);
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extern int cgroup_load_subsys(struct cgroup_subsys *ss);
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extern void cgroup_unload_subsys(struct cgroup_subsys *ss);
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extern const struct file_operations proc_cgroup_operations;
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/* Define the enumeration of all builtin cgroup subsystems */
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#define SUBSYS(_x) _x ## _subsys_id,
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enum cgroup_subsys_id {
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#include <linux/cgroup_subsys.h>
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CGROUP_BUILTIN_SUBSYS_COUNT
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};
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#undef SUBSYS
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/*
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* This define indicates the maximum number of subsystems that can be loaded
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* at once. We limit to this many since cgroupfs_root has subsys_bits to keep
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* track of all of them.
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*/
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#define CGROUP_SUBSYS_COUNT (BITS_PER_BYTE*sizeof(unsigned long))
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/* Per-subsystem/per-cgroup state maintained by the system. */
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struct cgroup_subsys_state {
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/*
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* The cgroup that this subsystem is attached to. Useful
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* for subsystems that want to know about the cgroup
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* hierarchy structure
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*/
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struct cgroup *cgroup;
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/*
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* State maintained by the cgroup system to allow subsystems
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* to be "busy". Should be accessed via css_get(),
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* css_tryget() and and css_put().
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*/
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atomic_t refcnt;
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unsigned long flags;
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/* ID for this css, if possible */
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struct css_id *id;
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};
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/* bits in struct cgroup_subsys_state flags field */
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enum {
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CSS_ROOT, /* This CSS is the root of the subsystem */
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CSS_REMOVED, /* This CSS is dead */
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};
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/* Caller must verify that the css is not for root cgroup */
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static inline void __css_get(struct cgroup_subsys_state *css, int count)
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{
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atomic_add(count, &css->refcnt);
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}
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/*
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* Call css_get() to hold a reference on the css; it can be used
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* for a reference obtained via:
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* - an existing ref-counted reference to the css
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* - task->cgroups for a locked task
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*/
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static inline void css_get(struct cgroup_subsys_state *css)
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{
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/* We don't need to reference count the root state */
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if (!test_bit(CSS_ROOT, &css->flags))
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__css_get(css, 1);
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}
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static inline bool css_is_removed(struct cgroup_subsys_state *css)
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{
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return test_bit(CSS_REMOVED, &css->flags);
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}
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/*
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* Call css_tryget() to take a reference on a css if your existing
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* (known-valid) reference isn't already ref-counted. Returns false if
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* the css has been destroyed.
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*/
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static inline bool css_tryget(struct cgroup_subsys_state *css)
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{
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if (test_bit(CSS_ROOT, &css->flags))
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return true;
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while (!atomic_inc_not_zero(&css->refcnt)) {
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if (test_bit(CSS_REMOVED, &css->flags))
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return false;
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cpu_relax();
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}
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return true;
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}
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/*
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* css_put() should be called to release a reference taken by
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* css_get() or css_tryget()
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*/
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extern void __css_put(struct cgroup_subsys_state *css, int count);
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static inline void css_put(struct cgroup_subsys_state *css)
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{
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if (!test_bit(CSS_ROOT, &css->flags))
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__css_put(css, 1);
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}
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/* bits in struct cgroup flags field */
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enum {
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/* Control Group is dead */
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CGRP_REMOVED,
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/*
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* Control Group has previously had a child cgroup or a task,
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* but no longer (only if CGRP_NOTIFY_ON_RELEASE is set)
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*/
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CGRP_RELEASABLE,
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/* Control Group requires release notifications to userspace */
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CGRP_NOTIFY_ON_RELEASE,
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/*
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* A thread in rmdir() is wating for this cgroup.
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*/
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CGRP_WAIT_ON_RMDIR,
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};
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/* which pidlist file are we talking about? */
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enum cgroup_filetype {
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CGROUP_FILE_PROCS,
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CGROUP_FILE_TASKS,
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};
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/*
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* A pidlist is a list of pids that virtually represents the contents of one
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* of the cgroup files ("procs" or "tasks"). We keep a list of such pidlists,
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* a pair (one each for procs, tasks) for each pid namespace that's relevant
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* to the cgroup.
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*/
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struct cgroup_pidlist {
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/*
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* used to find which pidlist is wanted. doesn't change as long as
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* this particular list stays in the list.
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*/
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struct { enum cgroup_filetype type; struct pid_namespace *ns; } key;
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/* array of xids */
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pid_t *list;
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/* how many elements the above list has */
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int length;
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/* how many files are using the current array */
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int use_count;
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/* each of these stored in a list by its cgroup */
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struct list_head links;
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/* pointer to the cgroup we belong to, for list removal purposes */
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struct cgroup *owner;
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/* protects the other fields */
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struct rw_semaphore mutex;
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};
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struct cgroup {
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unsigned long flags; /* "unsigned long" so bitops work */
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/*
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* count users of this cgroup. >0 means busy, but doesn't
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* necessarily indicate the number of tasks in the cgroup
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*/
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atomic_t count;
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/*
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* We link our 'sibling' struct into our parent's 'children'.
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* Our children link their 'sibling' into our 'children'.
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*/
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struct list_head sibling; /* my parent's children */
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struct list_head children; /* my children */
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struct cgroup *parent; /* my parent */
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struct dentry *dentry; /* cgroup fs entry, RCU protected */
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/* Private pointers for each registered subsystem */
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struct cgroup_subsys_state *subsys[CGROUP_SUBSYS_COUNT];
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struct cgroupfs_root *root;
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struct cgroup *top_cgroup;
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/*
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* List of cg_cgroup_links pointing at css_sets with
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* tasks in this cgroup. Protected by css_set_lock
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*/
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struct list_head css_sets;
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/*
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* Linked list running through all cgroups that can
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* potentially be reaped by the release agent. Protected by
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* release_list_lock
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*/
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struct list_head release_list;
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/*
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* list of pidlists, up to two for each namespace (one for procs, one
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* for tasks); created on demand.
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*/
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struct list_head pidlists;
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struct mutex pidlist_mutex;
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/* For RCU-protected deletion */
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struct rcu_head rcu_head;
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/* List of events which userspace want to recieve */
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struct list_head event_list;
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spinlock_t event_list_lock;
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};
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/*
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* A css_set is a structure holding pointers to a set of
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* cgroup_subsys_state objects. This saves space in the task struct
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* object and speeds up fork()/exit(), since a single inc/dec and a
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* list_add()/del() can bump the reference count on the entire cgroup
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* set for a task.
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*/
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struct css_set {
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/* Reference count */
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atomic_t refcount;
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/*
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* List running through all cgroup groups in the same hash
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* slot. Protected by css_set_lock
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*/
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struct hlist_node hlist;
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/*
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* List running through all tasks using this cgroup
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* group. Protected by css_set_lock
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*/
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struct list_head tasks;
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/*
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* List of cg_cgroup_link objects on link chains from
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* cgroups referenced from this css_set. Protected by
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* css_set_lock
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*/
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struct list_head cg_links;
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/*
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* Set of subsystem states, one for each subsystem. This array
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* is immutable after creation apart from the init_css_set
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* during subsystem registration (at boot time) and modular subsystem
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* loading/unloading.
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*/
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struct cgroup_subsys_state *subsys[CGROUP_SUBSYS_COUNT];
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/* For RCU-protected deletion */
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struct rcu_head rcu_head;
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};
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/*
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* cgroup_map_cb is an abstract callback API for reporting map-valued
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* control files
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*/
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struct cgroup_map_cb {
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int (*fill)(struct cgroup_map_cb *cb, const char *key, u64 value);
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void *state;
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};
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/*
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* struct cftype: handler definitions for cgroup control files
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*
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* When reading/writing to a file:
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* - the cgroup to use is file->f_dentry->d_parent->d_fsdata
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* - the 'cftype' of the file is file->f_dentry->d_fsdata
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*/
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#define MAX_CFTYPE_NAME 64
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struct cftype {
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/*
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* By convention, the name should begin with the name of the
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* subsystem, followed by a period
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*/
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char name[MAX_CFTYPE_NAME];
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int private;
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/*
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* If not 0, file mode is set to this value, otherwise it will
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* be figured out automatically
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*/
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mode_t mode;
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/*
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* If non-zero, defines the maximum length of string that can
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* be passed to write_string; defaults to 64
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*/
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size_t max_write_len;
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int (*open)(struct inode *inode, struct file *file);
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ssize_t (*read)(struct cgroup *cgrp, struct cftype *cft,
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struct file *file,
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char __user *buf, size_t nbytes, loff_t *ppos);
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/*
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* read_u64() is a shortcut for the common case of returning a
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* single integer. Use it in place of read()
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*/
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u64 (*read_u64)(struct cgroup *cgrp, struct cftype *cft);
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/*
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* read_s64() is a signed version of read_u64()
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*/
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s64 (*read_s64)(struct cgroup *cgrp, struct cftype *cft);
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/*
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* read_map() is used for defining a map of key/value
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* pairs. It should call cb->fill(cb, key, value) for each
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* entry. The key/value pairs (and their ordering) should not
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* change between reboots.
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*/
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int (*read_map)(struct cgroup *cont, struct cftype *cft,
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struct cgroup_map_cb *cb);
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/*
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* read_seq_string() is used for outputting a simple sequence
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* using seqfile.
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*/
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int (*read_seq_string)(struct cgroup *cont, struct cftype *cft,
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struct seq_file *m);
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ssize_t (*write)(struct cgroup *cgrp, struct cftype *cft,
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struct file *file,
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const char __user *buf, size_t nbytes, loff_t *ppos);
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/*
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* write_u64() is a shortcut for the common case of accepting
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* a single integer (as parsed by simple_strtoull) from
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* userspace. Use in place of write(); return 0 or error.
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*/
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int (*write_u64)(struct cgroup *cgrp, struct cftype *cft, u64 val);
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/*
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* write_s64() is a signed version of write_u64()
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*/
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int (*write_s64)(struct cgroup *cgrp, struct cftype *cft, s64 val);
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/*
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* write_string() is passed a nul-terminated kernelspace
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* buffer of maximum length determined by max_write_len.
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* Returns 0 or -ve error code.
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*/
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int (*write_string)(struct cgroup *cgrp, struct cftype *cft,
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const char *buffer);
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/*
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* trigger() callback can be used to get some kick from the
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* userspace, when the actual string written is not important
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* at all. The private field can be used to determine the
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* kick type for multiplexing.
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*/
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int (*trigger)(struct cgroup *cgrp, unsigned int event);
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int (*release)(struct inode *inode, struct file *file);
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/*
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* register_event() callback will be used to add new userspace
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* waiter for changes related to the cftype. Implement it if
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* you want to provide this functionality. Use eventfd_signal()
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* on eventfd to send notification to userspace.
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*/
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int (*register_event)(struct cgroup *cgrp, struct cftype *cft,
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struct eventfd_ctx *eventfd, const char *args);
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/*
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* unregister_event() callback will be called when userspace
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* closes the eventfd or on cgroup removing.
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* This callback must be implemented, if you want provide
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* notification functionality.
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*/
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int (*unregister_event)(struct cgroup *cgrp, struct cftype *cft,
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struct eventfd_ctx *eventfd);
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};
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struct cgroup_scanner {
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struct cgroup *cg;
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int (*test_task)(struct task_struct *p, struct cgroup_scanner *scan);
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void (*process_task)(struct task_struct *p,
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struct cgroup_scanner *scan);
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struct ptr_heap *heap;
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void *data;
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};
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/*
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* Add a new file to the given cgroup directory. Should only be
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* called by subsystems from within a populate() method
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*/
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int cgroup_add_file(struct cgroup *cgrp, struct cgroup_subsys *subsys,
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const struct cftype *cft);
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/*
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* Add a set of new files to the given cgroup directory. Should
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* only be called by subsystems from within a populate() method
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*/
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int cgroup_add_files(struct cgroup *cgrp,
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struct cgroup_subsys *subsys,
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const struct cftype cft[],
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int count);
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int cgroup_is_removed(const struct cgroup *cgrp);
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int cgroup_path(const struct cgroup *cgrp, char *buf, int buflen);
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int cgroup_task_count(const struct cgroup *cgrp);
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/* Return true if cgrp is a descendant of the task's cgroup */
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int cgroup_is_descendant(const struct cgroup *cgrp, struct task_struct *task);
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/*
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* When the subsys has to access css and may add permanent refcnt to css,
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* it should take care of racy conditions with rmdir(). Following set of
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* functions, is for stop/restart rmdir if necessary.
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* Because these will call css_get/put, "css" should be alive css.
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*
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* cgroup_exclude_rmdir();
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* ...do some jobs which may access arbitrary empty cgroup
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* cgroup_release_and_wakeup_rmdir();
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*
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* When someone removes a cgroup while cgroup_exclude_rmdir() holds it,
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* it sleeps and cgroup_release_and_wakeup_rmdir() will wake him up.
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*/
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void cgroup_exclude_rmdir(struct cgroup_subsys_state *css);
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void cgroup_release_and_wakeup_rmdir(struct cgroup_subsys_state *css);
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/*
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* Control Group subsystem type.
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* See Documentation/cgroups/cgroups.txt for details
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*/
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struct cgroup_subsys {
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struct cgroup_subsys_state *(*create)(struct cgroup_subsys *ss,
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struct cgroup *cgrp);
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int (*pre_destroy)(struct cgroup_subsys *ss, struct cgroup *cgrp);
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void (*destroy)(struct cgroup_subsys *ss, struct cgroup *cgrp);
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int (*can_attach)(struct cgroup_subsys *ss, struct cgroup *cgrp,
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struct task_struct *tsk, bool threadgroup);
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void (*cancel_attach)(struct cgroup_subsys *ss, struct cgroup *cgrp,
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struct task_struct *tsk, bool threadgroup);
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void (*attach)(struct cgroup_subsys *ss, struct cgroup *cgrp,
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struct cgroup *old_cgrp, struct task_struct *tsk,
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bool threadgroup);
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void (*fork)(struct cgroup_subsys *ss, struct task_struct *task);
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void (*exit)(struct cgroup_subsys *ss, struct task_struct *task);
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int (*populate)(struct cgroup_subsys *ss,
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struct cgroup *cgrp);
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void (*post_clone)(struct cgroup_subsys *ss, struct cgroup *cgrp);
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void (*bind)(struct cgroup_subsys *ss, struct cgroup *root);
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int subsys_id;
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int active;
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int disabled;
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int early_init;
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/*
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* True if this subsys uses ID. ID is not available before cgroup_init()
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* (not available in early_init time.)
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*/
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bool use_id;
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#define MAX_CGROUP_TYPE_NAMELEN 32
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const char *name;
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/*
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* Protects sibling/children links of cgroups in this
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* hierarchy, plus protects which hierarchy (or none) the
|
|
* subsystem is a part of (i.e. root/sibling). To avoid
|
|
* potential deadlocks, the following operations should not be
|
|
* undertaken while holding any hierarchy_mutex:
|
|
*
|
|
* - allocating memory
|
|
* - initiating hotplug events
|
|
*/
|
|
struct mutex hierarchy_mutex;
|
|
struct lock_class_key subsys_key;
|
|
|
|
/*
|
|
* Link to parent, and list entry in parent's children.
|
|
* Protected by this->hierarchy_mutex and cgroup_lock()
|
|
*/
|
|
struct cgroupfs_root *root;
|
|
struct list_head sibling;
|
|
/* used when use_id == true */
|
|
struct idr idr;
|
|
spinlock_t id_lock;
|
|
|
|
/* should be defined only by modular subsystems */
|
|
struct module *module;
|
|
};
|
|
|
|
#define SUBSYS(_x) extern struct cgroup_subsys _x ## _subsys;
|
|
#include <linux/cgroup_subsys.h>
|
|
#undef SUBSYS
|
|
|
|
static inline struct cgroup_subsys_state *cgroup_subsys_state(
|
|
struct cgroup *cgrp, int subsys_id)
|
|
{
|
|
return cgrp->subsys[subsys_id];
|
|
}
|
|
|
|
static inline struct cgroup_subsys_state *task_subsys_state(
|
|
struct task_struct *task, int subsys_id)
|
|
{
|
|
return rcu_dereference_check(task->cgroups->subsys[subsys_id],
|
|
rcu_read_lock_held() ||
|
|
cgroup_lock_is_held());
|
|
}
|
|
|
|
static inline struct cgroup* task_cgroup(struct task_struct *task,
|
|
int subsys_id)
|
|
{
|
|
return task_subsys_state(task, subsys_id)->cgroup;
|
|
}
|
|
|
|
int cgroup_clone(struct task_struct *tsk, struct cgroup_subsys *ss,
|
|
char *nodename);
|
|
|
|
/* A cgroup_iter should be treated as an opaque object */
|
|
struct cgroup_iter {
|
|
struct list_head *cg_link;
|
|
struct list_head *task;
|
|
};
|
|
|
|
/*
|
|
* To iterate across the tasks in a cgroup:
|
|
*
|
|
* 1) call cgroup_iter_start to intialize an iterator
|
|
*
|
|
* 2) call cgroup_iter_next() to retrieve member tasks until it
|
|
* returns NULL or until you want to end the iteration
|
|
*
|
|
* 3) call cgroup_iter_end() to destroy the iterator.
|
|
*
|
|
* Or, call cgroup_scan_tasks() to iterate through every task in a
|
|
* cgroup - cgroup_scan_tasks() holds the css_set_lock when calling
|
|
* the test_task() callback, but not while calling the process_task()
|
|
* callback.
|
|
*/
|
|
void cgroup_iter_start(struct cgroup *cgrp, struct cgroup_iter *it);
|
|
struct task_struct *cgroup_iter_next(struct cgroup *cgrp,
|
|
struct cgroup_iter *it);
|
|
void cgroup_iter_end(struct cgroup *cgrp, struct cgroup_iter *it);
|
|
int cgroup_scan_tasks(struct cgroup_scanner *scan);
|
|
int cgroup_attach_task(struct cgroup *, struct task_struct *);
|
|
|
|
/*
|
|
* CSS ID is ID for cgroup_subsys_state structs under subsys. This only works
|
|
* if cgroup_subsys.use_id == true. It can be used for looking up and scanning.
|
|
* CSS ID is assigned at cgroup allocation (create) automatically
|
|
* and removed when subsys calls free_css_id() function. This is because
|
|
* the lifetime of cgroup_subsys_state is subsys's matter.
|
|
*
|
|
* Looking up and scanning function should be called under rcu_read_lock().
|
|
* Taking cgroup_mutex()/hierarchy_mutex() is not necessary for following calls.
|
|
* But the css returned by this routine can be "not populated yet" or "being
|
|
* destroyed". The caller should check css and cgroup's status.
|
|
*/
|
|
|
|
/*
|
|
* Typically Called at ->destroy(), or somewhere the subsys frees
|
|
* cgroup_subsys_state.
|
|
*/
|
|
void free_css_id(struct cgroup_subsys *ss, struct cgroup_subsys_state *css);
|
|
|
|
/* Find a cgroup_subsys_state which has given ID */
|
|
|
|
struct cgroup_subsys_state *css_lookup(struct cgroup_subsys *ss, int id);
|
|
|
|
/*
|
|
* Get a cgroup whose id is greater than or equal to id under tree of root.
|
|
* Returning a cgroup_subsys_state or NULL.
|
|
*/
|
|
struct cgroup_subsys_state *css_get_next(struct cgroup_subsys *ss, int id,
|
|
struct cgroup_subsys_state *root, int *foundid);
|
|
|
|
/* Returns true if root is ancestor of cg */
|
|
bool css_is_ancestor(struct cgroup_subsys_state *cg,
|
|
const struct cgroup_subsys_state *root);
|
|
|
|
/* Get id and depth of css */
|
|
unsigned short css_id(struct cgroup_subsys_state *css);
|
|
unsigned short css_depth(struct cgroup_subsys_state *css);
|
|
|
|
#else /* !CONFIG_CGROUPS */
|
|
|
|
static inline int cgroup_init_early(void) { return 0; }
|
|
static inline int cgroup_init(void) { return 0; }
|
|
static inline void cgroup_fork(struct task_struct *p) {}
|
|
static inline void cgroup_fork_callbacks(struct task_struct *p) {}
|
|
static inline void cgroup_post_fork(struct task_struct *p) {}
|
|
static inline void cgroup_exit(struct task_struct *p, int callbacks) {}
|
|
|
|
static inline void cgroup_lock(void) {}
|
|
static inline void cgroup_unlock(void) {}
|
|
static inline int cgroupstats_build(struct cgroupstats *stats,
|
|
struct dentry *dentry)
|
|
{
|
|
return -EINVAL;
|
|
}
|
|
|
|
#endif /* !CONFIG_CGROUPS */
|
|
|
|
#endif /* _LINUX_CGROUP_H */
|